Process of drying lumber



F. K. FISH, In. PROCESS OF DRYING LUMBER. APPLICATION FILED um. I8. 1918. RENEWED AUG. 13. m9.

Patented 'Jan. 20, 1920..v

3 SHEETS-SHEET I.

Q v Q\ F. K. FISH, In.

PBOCESSOF DRYING LUMBER.

APPLICATION men um. 18. ms. RENEWED Aue. I3. I919.

'1,32 8,507.-- Patented Ja11.20,1920.

3 SHEETS-SHEET 2.

I l" x 3 SHEETSSHEEfi Patented Jan. 20, 1920.

affonlcq city, in

of New ed previous tire wood structure and the wood a high temperature,

UNITED STATES mm orr on.

FREDERICK FISH, .78., OF NEW YORK, N. Y.

PROCESS OF DRYING LUMBER.

Specification of Letters Patent.

Application filled January 18, 1918, Serial No. 212,467. Renewed August 13, 1919. Serial 110.317392.

To all whom it may concern:

' Be it known that I, FREDERICK K. FISH, J12, a citizen of the ,United States of America, residing at 2 Stone, street, New ork the county'of New York and State- York, have invented certain newjand useful Improvements in Processes of Drying Lumber, of which the following is a specification.

This invention relates to improvements in a process for drying and treating wood.

In my companion application for Patent Serial Number 261,938, renewed November 9th, 1918, I have described and claimed a process for treating wood, in which the wood is subjected to a partial vacuumftb expel a part of of treating the wood in supzrheatedwater; the water in the early case ing boiled previous to its introduction to the container; and the wood was finally treated in an equalizing'chamber, and there dried.

It has been found to be advantageous'to preliminarily treat the green wood to a sweating step, previous to subjecting it to the action of the water, and it has also been demonstrated that if the water is superheatto its introduction to the. container, quicker and more efiective results are obtained. Furthermore, to expedite the final drying, and to insure against checking the wood under differing climatic and atmospheric conditions, I have provided a cooling step. a,

Therefore one of the principal objects of the present invention is to provide a preliminary step to'heat and soften the green wood, and otherwise put it in good condition to render it more susceptible to the wa ter treatment. In this'p'relimin'ary step, the green wood is laced in a closed sweating c amber in which steam has been introduced to create a moderately heated moist atmos ere to raise the temperadissolve the gummy sap to free them from-their confinement. This step in the process is continued long enough to cause the heated moist atmosphere to-thoroughly permeate the en the warmth and soft and pliable. the interior of matters and tend moisture render the wood This treatment creates 1n toa the woodis removed I this condition,-

- structure the air previous to the step' substantially ture of the woo throughout without danger of checking, and to soften the structure, open up the pores,

and while in.

closed container, um, which expels and otherwise conditions the structure for the action of the water.

. Next the wood is subjected tothe action of superheated. water, to expel the gummy sap matters, and melt the contained resins. It has been found advantageous, both as to effect and expediency to superheat the water previous to introducing it to the wood. The interior of the wood at the time the water is introduced is highly heated and its is materially softened, consequently when the superheated water is introduced' into the container, ,,itpromptly penetrates the wood structure without liability of internal checking, .and the gummy tion commences.- This is due to the fact Patented Jan. 20, 1920.

and is subjected to a vacua portion of the moisture,

'that the water is under pressure, andis heated above the boiling point, and as the wood structure is able condition, the water soluble gums and the resins are attacked without lossof time. The previously heated wood and superheated water, therefore accomplishes two things, i. e., savesrloss of time in treating the wood; and avoids all possibilit pf internal checking, accomplishments w have decided advantages in producing practical results.

The cooling or tempering step in the present invention is one which adds materially to the efiective curing or seasoning of the wood. For instance after the wood is removed from the equalizing chamber, the mamoved, and its contained resins are distributed throughout the wood structure, and its interior is highly heated. The new subheated and otherwise in perme-.

' jor portion of its water soluble matter is restantially reconstructed wood structure is 11- able to surface cracking when renrbved to the air, due to the differences between the internal and external temperature, and to avoid this possibility, the wood, accordm to the present invention is gradually coole or tempered, to avoid the setting up of unequal stresses. This step is continued until about the time the internal and external temperature becomes equalized, which results in there sins setting in the spaces n the wood,,previously occupied'by the water soluble substances, wit out the wood in any- .wise checkingv or. cracking.

In the foregoing e phasized the new steps in the present 1mdescripti'onI have only 7 structure of'the wood, it may, I of the present invention,

of the wood.

confinement, and separatedfrom their provement, the entire tained resins,

process being hereinafterdescribed in detail.

Structurally, wood consists mainl of cellulose with its incrusting layers 0 lignin, and sap containing. water, resins, tannins, coloring matter with other organic substances, together with a minor tion of mineral matter 'or ash. L1

while not fully understood chemically, is

closely allied to the cellulose of the wood, and since it forms a part of the permanent for purposes 'be regarded as identical with the cellulose. I

Of the other organic substances, the principal are starches,- gummy substances and 'albuminous compounds found in the watery sap and in the wood structure, together with resins or resinous compounds mainly to be found in the resin cells or ducts. The starches, gums and albuminous substances with the cipally necessary. to the life of the grow ing tree. but their presence infelled wood, timber or lumber, if in any quantity, is largely deterim'ental' as affording principal elements leadin to the decay or destruction herefore, any proper treatment of the wood to preserve the same should be directed. to the removal of the starches, gums, albuminous substances and sap water with the proper preservation 01' resinous substances and the structural elements, care being taken to the end that the wood is' not-kept under treatment lon enough to disintegrate or destroy the W0 as such, so that the elasticity, strength andrthat which is termed, life is removed.

In carrying out my improved process, cer-' tain steps are provided to utilize the natural bases of the resins, acetic acid and tannic acid existing in the wood, as preservative agents; that is to say, these constituents or sub stances are dislodged from their cellular or1 inal' 'vehicle, the water soluble constituen t s being dissolved, and the major. portion removedfrom the wood, the remainder being distributed through, and deposited upon the fibrous structure of the wood.

With a fu of wood, the designed to expel the water soluble constituents, and replace same with the conto insure of the'proper treatment and? drying of the wood, without cracking, checkingor other physicaldeteriaccording to the im proved process is substantially non-hydrooration. Wood treated scopic, and correspondingly immune from spores, or fermentation or the like, and

' undergoes the minimum amount of shrink-' age.

Pr pe watery sap are elements prinll appreciation of the structure various steps in the process are -'lar in principle Figure 1 is a vertical longitudinal section of a sterilizer, suitable for carrying out certain of the steps of the process. Fig. 2 is a. fdiagrammatlc illustratlon of the apparatusassociated with the sterilizer for controlling it.

Fig. 3 is a transverse section of the sterilizer. Y Fig. 4 is a vertical-longitudinal section of an equalizingchamber.

Fig. 5 is a section on the line 55, Fi 4.

ig. 6 is a diagrammatic plan view of the various containers, showing their means of 1 inter-communication.

a side elevation of the same.

1' rep nts a sterilizer of construction suitable for containing superheated water, and is preferably provided with a presser plate 2, with means for adjusting same, such for instance as screws 3. By thls means the charge of wood maybe kept under pressure and prevented fro ing distorted while being treate the process, it is provided with an exhaust pip a vacuum pump, 7 with an lnterposed condenser 8; a water supply pipe 9 that communicates with a vertical 1 for conveniently developing the several conditions incident to the different steps of floatin or becom- The con-. tamer or sterilizer is provided with heatingcoils 4, by which the temperature of the e 6 leading to 10 leading to 1 pipe an'elevated water supply tan and also with a pump 11, by means of which water once supplied to the sterilizer 1, drawn, and forthe sake of turned to the [elevated tank for reuse. Water supplied;.through pipes 9 and 10 to the sterilizer 1, will preferably be previously superheated and the coils 4 maintain' g its .lge'at or raising it to the proper degree. e pipes 6, 9 and 10, ,as' well as the connections with the return pipev for the water, are provided with suitable valves to open and close them appropriately to the several steps of the process. 12 representstracks to receive the car or truck upon which the wood is loaded for introduction into the sterilizer.

Referrin the equalizing chamber which is preferably provided with a to that employed in the sterilizer 1, with heating-pipes 14 preferably located at the bottom, an air inlet or damper. 15, and an air outlet or damper 16. This may be witheconomy, re-Li 10 relied upon for to Figs. 4 and 5, 13 represents equalizing chamber is furtherprovided with tracks 17 for convenient introduction of the charge of wood, and its walls are preferably constructed 50 as to have a high co-efiicient of heat insulation for the sake of economy in operation.

Referring to Fig. 6, 18 represents the sweat chamber; 19 a transfer platform for transferring a truck load of wood to equalizing chambers '20, when withdrawn from sterilizer 1; 21 are tracks upon which platform 19 is adapted to travel; and 22 are cooling or tempering chambers". Equalizing chambers and cooling chambers and 22 res ectively, are provided with tracks 23, exten ing therethrough for the convenient introduction thereinto of a truck load of wood. 17 isa track extending throu h sweat vacuumis now created chamber 18, sterilizer 1, and transfer platform 19, for the convenient introduction therethrough of a truck load of wood.

In carrying out the process with the apparatus above described, a charge of wood is loaded on a truck, and is introduced into the sweat chamber 18, the sweat chamber having previously had created therein a moderately eated moist atmosphere, steam being employed for this purpose. The wood having been introduced -to the moist atmosphere, the chamber is closed and the wood is subjected to the moist heat until it becomes heated and saturated throughout its entire structure. The moist atmosphere penetrates the fibrous structure and softens the wood, sweats the fibers, and opens up thepores, and tends to soften the sap matter and resins.

The Wood is retained in the sweat chamber suflicient time to insure of it being internally heated throughout, and well conditioned for future'treatment. The wood is removed from the chamber, and while in a heated condition, and well moistened, it is quickly introduced into the container or sterilizer 1,'the pressing devices are operated to hold down the wood and then the container is hermetically sealed. A partial in the container, the vacuum pump 7 being operated to accomplish this function.

The partial vacuum is continued for ficient time to evaporate a portion of the aqueous content of with it the resins or the resin-producing constituents. superheated water is now introduced into the container to completely submerge the wood, the water being forced in either by pressure from the tank above, or by operating the pump 11. The wood remains in the water for approximately onehour, and pressure of about twenty 'pounds is maintained. The pressure is provided by the ump 11, and is maintained by continuing -the heating through means of the heating coils a.

In this step of the process, the super water, and readily melt and and without taking with it say about 290 F.

suf-

the wood, without talnng j forated pipes, able to. giving up moisture, is again subheated water commences to act immediately on the wood, as the latter, it will be remembered has been previously heated and sof tened, and is favorable for prompt action of the water. The highly heated water under pressure, is forced through the wood structure, and the gummy sap matter is dissolved and mixed with the water, and consequentl is displaced andyremoved from the woo The resins are also subjected to the heated spread throughout the wood, taking the place of the displaced and dissolved gummy sap .matter. The individual fibers are swelled or enlarged by the action of the water, heat and pressure without in anywise checking or cracking the structure, and in addition the confined water causes a depos' face of the latter, giving the wood a distinctive appearance.

After the wood is subjected to the superheated water, the valves are manipulated, and the pressure in the container, or the pump 11 may be employed, forces the water back into the tank and it may be reused. second vacuum is now created, preferably of about twenty, inches, and for a period sufficient to expel or evaporate a greater portion of the moisture content of the wood, the values of the sap, such as the resins-and resin producing substances. i l

To continue the withdrawal of the moisture from the interior of the wood and prevent cracking and checking, the secondmentioned vacuum is. gradually replaced by an artificial atmosphere of high temperature, This condition is created by introducing steam to the container through the perforated pipes, the temperature being kept up by passing steam through tion of the colloidal substances of the fibers of the wood, and tans the surthe heating C01l$ 4;. Some pressure is mamhalf-hour thereof. This vacuum has the ef-- fectof aiding in uniformly distributing the resins through the wood structure, and when completed, the wood is in condition to be removed from the sterilizer. v

The load of wood is now rapidly transferred to the equalizing chamber. When in of the wood well above This step is continued for about the chambers, the dampers and 16 are this chamber the wood is subjected to an atmosphere at a temperature sufiicient to cause continuous evaporation of moisture through the entire structure, at the same time keeping the retained resins and resin substances in a melted condition. This is accomplished by passing steam through the coils 14, and at the same time a current of heated air is periodically forced through the chamber by means of pipes (not shown), or by operating the dampers 15 and 16.

Upon the first introduction, of the wood in closed and the evaporated moisture rapidly creates a humid condition within the chamher. As the humidity increases moisture .occurs on the surface of the wood, anggas the point of saturation is approached, ev poration of the moisture ceases. At such ime the dampers are operated to relieve the c0ndi-- tion within the chamber, and this may be secured either by opening the upper damper alone, or by periodically opening both damers or introducin' a se arate current of air around the wood, which accelerates the evaporation of 'the moisture, as fully set out in my co-pending application for patent above identified. 4

During the treatment of the wood in the equalizing chamber, the meltedresins permeate the cellulose, and are caused to spread check the wood structure.-

into the places previously occupied by the;

watersoluble constituents, and it is now that the next and final step is brought in to insure against checking or cracking when bringing the wood to. atmospheric temper- After treatment in the equalizing cham her, the wood is quickly conveyed to the cooling or tempering chamber. This chamber is'preferably of suflicient size to take a number of loads of wood, and as a loader loads is or'are removed tothe atmosphere, the others are advanced toward the, exit.

Steam is introduced to the cooling cham- 1 her to .create a moist moderately heatedat mosphere which is so regulatedas-"fto allow.

of the gradual reduction of the internal tem perature of the wood; as moistu'reevaporat-' mg from the wood, together with the steam creates a humid condition around thewood,

' perature, which results in a'gradu'al. setting atmosphere it wi Which is harmonized with the-internal temof the distributed resins.

This'step is kept. up sufficient time tobri'ng the resins will s in f the .11.. greatly facilitate the treating nd' dr 'and-then again'subjecting the wood to the e5;actiOn Of aivacUum. wood saves'considerable time'-in complet'1ng 5 8 The of treating wood compris-lso' permit the the temperature. of they woodto atmospheric tem erature, v consequentlythe wood. is artificia 1y dried throughout, and: into the rinka'n'd 4 thetemperature therein,

to the action .of a vacuum, thereafter sub-- the process as it is evident the fibrous structure will be more susceptible to the action of the superheated water, and the latter will at once dissolve and remove the water soluble constituents, and melt the resins; Furthermore the cooling or tempering step will so gradually reduce and harmonize the temperature of the wood with that of the atmosphere that the resins in setting during the final drying will not shrink, crack or What I claim 'is:

1. The process of treating wood which comprises applying to wood perheated condition, then submerging the wood therewith, and permeating the wood throughout and arrestm g'thetreatment and removing the water before any substantial destruction of the fibers occurs to remove the ,ma]' or portion of the fermentablesubstances.

2. The process of treating wood which comprises superheating liquid and appl ing the liquidwhile superheated to wood which has been preheated to sweat the same, and submerging the wood therewith, to permeate the wood throughout.

3. The process which comprises superheating liquid which has been previously used in the wood treatment, applying the liquid while superheated to wood, preheated to a temperature to receive the superheated liquid without danger of checking or "cracking, submerging the woodtherewith, and removing.

the superheated liquid. v 4. The process which comprises superheating liquid which has been therewith, and

removing the superheated liquid.

5. The process. of treating and drying wood which comprises softening .lts structure, then dissolving and removing from'the water in a susoftened wood water soluble :constitutents,

and then drying the wood at a'temperature suflicient toinduce ay evaporation and 'to spreading of theii'tesins to permeate thefibersofthe wood.

wopd comprising sweat ng the woodlto soften itt'submerging 6. The process of treating the wood in liquidto dissolve and extract the soluble gums and sap,

and then-subjectresins to permeate the .ingthe wood to a temperature to induce evaporation of the moisture of the wood and prevent hardening of the resins to permit the spreading 7 i The process of treating wood comprisingsweating the wood to subjecting the wood merging' the {wood in liquid under pressure,

soften it and raise ing sweating the wood to soften it and raise the temperature therein, subjecting the wood to the action of a vacuum, thereafter submerging the wood in liquid under pressure, then again subjecting the wood to the "action of a vacuum, and finally drying'the wood.

9. The process of treating wood which comprises preheating wood to sweat it and applying to and surrounding the wood while in such heated condition with superheated water, which has similarly been used, removing the superheated water and consequently drying the wood.

10. The process of drying wood comprising preheating the wood to sweat it, then subjecting the wood to superheated water and subsequently subjecting the wood to heat at a temperature sufiicient to induce evaporation and prevent hardening of the resins. j

11. The proces of treating wood which comprises preheating wood to sweat it and applying to and surrounding the wood while in such heated condition with superheated water, removing the water, and subsequently drying the wood.

12. The process of treating wood which comprises preheating wood applying to and surrounding the wood with superheated water, which has been similarly used, removing the superheated water and subsequently subjecting the wood-to a temperature sufficient to induce evaporation of the moisture in the wood and prevent hardening of the resins thereby causing the resins to permeate the fibers of the, wood; V

13. The process of treating wood com-- prising subjecting the wood to the action of a vacuum to remove the air therefrom, then submerging the wood in fluid under pressure to dissolve and extract the soluble gums and sap, subsequently drying the wood, and

' thereafter conditioning the wood.

its structure to prepare it of treating wood .comprising subjecting the wood to steam to soften its structure, to prepare it for subsequent treatment, submerging the wood in liquid under pressure to remove the soluble gums and sap, and subsequently subjecting the wood to a temperature to induce evaporation of the moisture of the wood and prevent hardening of the resins thereby causing the resins to permeate the individual fibers of the wood.

15. The rocess of treating wood comrising sub ecting wood to steam to soften for subsequent treatment, then submerging the wood in liquid under pressure to dissolve and extract the soluble gums and sap, then subjecting the wood to a vacuum, and finally drying the wood at a temperature to induce evaporation of the moisture of the wood and pre-- vent hardening of the resins thereby c'aus-,

14. The process to a drying temperature,

same,-

ing .the resins to permeate the fibers'of the e process of same, submerging treating wood compris-' ing sweatingthe wood to soften and heat the the wood in .heated wa-' ter, and subsequently subjecting the wood to a dryin temperature to produce a wood having the major portion of its gummy sap and other readily fermentable matters re-v moved and fused throughout the wood,

18. The process of treating wood comprising sweating the wood to soften and'heat the same, treating the wood to dissolve and remove water soluble constituents, quently drying the wood.

19. The process of treating wood comprisin sweating the wood to soften and heat the same, and submerging the wood in heated water under pressure to dissolve and remove water soluble constituents.

20. The ,process 'of treating wood comprising sweating the wood, then treating the wood to a vacuum, subjecting the wood to heated water, thereafter subjecting the wood and finally conditionin the wood.

21'. he process of treating wood comprising su'bjecting the wood to a vacuum, subjectin the wood to heated water to dis solve and remove water soluble constituents, subsequently treating the wood to a drying temperature, and thereafter conditioning the wood.

. 22. The process of treating wood comprising supplying heat to the wood at a temture frommround the wood and thereafter removing the wood and subjecting it to a confined moist atmosphere while the temperature is being reduced to condition the same.

' 23. The process of treating wood comprising sweating the wood to soften and heat the then to a vacuum,

ture is being reduced to condition the same.

its preservative substances d1f-' and subse- A then subjecting the wood to'heated water to dissolveand remove the water soluble constituents, subjecting 24. The process of treating wood comprising subjecting the wood to a vacuum, then to heated water to dissolve and remove the water soluble constituents, subjecting the wood to a vacuum, then to steam, then to a vacuum, subjecting the wood to a heated and moist atmosphere to evaporate moisture, and finally subjecting the wood to a confined moist atmosphere while the temperature is being reduced to condition the same.

25. The process of treating wood comprising subjecting the wood to heated water to dissolve and remove the water soluble constituents, subjecting the wood to a vacuum,

then to steam, then to a vacuum, subjecting the wood to a heated and moist atmosphere to evaporate moisture while removing excess moisture, and finally subjecting the wood to a confined moist atmosphere while the temperature is being reduced tocondition the same. 26. The process of treating wood comprising subjecting the wood to a vacuum, then to steam, then to a vacuum, subjecting the wood to a heated and moist atmosphere to evaporate moisture, and finally subjecting the wood to a confined moist atmosphere while the temperature is being reduced, to condition the same. v

27. The process of treating wood comprising sweating the wood to soften and heat the same, then subjecting the wood to a vacuum, then to heated water, then to a vacuum, and

' thereafter subjecting the wood'to steamv to evaporate moisture.

28. The process of treating wood comprising sweating the wood to soften and heat the same, then subjecting the wood to a vacuum, then to heated water, then to a vacuum, thereafter subjecting the wood to steam to evaporate moisture, and then to a vacuum.

29. The process of treating wood comprising sweating the wood to soften and heat the same, then subjecting the wood to a vacuum, then toheated water, then to a vacuum, thereafter subjecting the wood to steam to evaporate moisture," then to a vacuum, and thereafter subjecting the wood to a dlging temperature while removing moisture ing sweating the wood to so around the wood.-

30. The processof treatin wood comprisn and heat the same,.then subjecting the wood to a vacuum,

" 'and thereafter submerginglthe wood in heated water to'dissolve and'remove water soluble constituents.

the temperature of the wood and 'reducingth'e. heat of the wood an rounding moisture, until the-wood is unif ,ditionedf- 31. The processof treating wood while in a heated condition and of superficial dryness by subjecting. it toahumid' atmosphere a proaching saturation and of substantial y dually the suratmosphere' while .removin excess rm ly con- 32. The process of treating wood while in a heated condition and of superficial dryness by subjecting it to a humid and heated atmosphere of substantially the heat of the wood and gradually reducing the temperature, producing a drying. of the interior of the wood and a proper conditioning of the same.

33. The process of treatin wood comprising sweating the wood to so en and heat the same, then subjecting it toa vacuum, and thereaftersubjecting the wood to a drying temperature in a moist atmosphere and periodically removing excess moisture.

34. The process of treating wood comprising sweating the wood to soften and heat the same, thereafter subjecting the wood to a drying temperature, and then subjecting the wood to a humid and heated atmosphere of substantially the heat of the wood and gradually reducingthe temperature, producing subjecting the wood to a humid and heated atmosphere of substahtially the heat of the wood and gradually treducing the temperature producing a drying of the interior of the wood and a proper conditioning of the same.

37. The process of treating wood compris- :-ing sweating the wood tosoften and heat the same, thereafter subjecting the wood to heat under pressure to evaporate moisture, thereafter drying the wood in a moist atmosphere and periodically removing accumulating moisture.

38. The process of treating Wood comprisioo ing subjecting the wood to a vacuum and heat to expel air therefrom, thereafter subjecting the wood to a drying temperature, and finally'subjecting the wood to a humid and heated atmosphere of substantially the heat of the wood and gradually reducingthe temperature, producing a drying of the interior of the wood and a proper conditioning of the same. v 39. The process of treating wood comprising sweating the wood to soften and heat the same, submerging the wood in heated water under'pressure to dissolve and remove the water soluble constituents removing the water," and thereafter drying the wood at {about atmospheric pressure-and in the presence of heat while introducing a current of heated air.

40. The process of treating wood comprising subjecting the wood to a vacuum to expel a portion of the air therefrom, treating the wood to soften its structure and dissolve gummy sap matter, then to a vacuum, and then. subjecting the wood to heat at about atmospheric pressure while periodically removing the accumulating moisture surrounding the wood While introducing a current of heated air.

41. The process of treating wood com rising sweating the wood to soften and eat the same, then subjecting the wood to a vacuum, thensubmerging the wood in superheated water to dissolve and remove water soluble constituents, and thereafter drying and conditioning the wood.

' 42. The process of treating wood comprising sweating the wood to the same, thereafter submerging the wood in superheated water to dissolve and remove water soluble constituents, removing the water from around the wood, and'then subjecting the wood to a vacuum to withdraw mois ture therefrom.

4:3. The process of treating wood comprising reheatingl the wood, submerging the woo in super eated water to dissolve and remove water soluble constituents, removing the water and subsequently subjecting the wood to a drying heat.

44. The process of treating-wood comprising preheating the wood, submerging the wood in superheated water to dissolve and remove water soluble constituents, removing the water, and then subjecting the wood to a lurality of vacuum treatments alternated with a pressure around the wood, and thereafter subjecting thewood to a drying heat.

45. The process of treating wood comprising sweating the wood, thereafter submerging the wood in superheated water to dissolve and remove water soluble constituents,

.Wood to a plurality of vacuum treatments soften and heat- .re'moving excess removing the water, then subjecting the alternated with 'a raising of the pressure around the wood, the temperature of the wood during these steps being maintained up to a degree sufiicient to induce evaporation and prevent hardening of the resins, finally conditioning the wood in a moderately heated moist atmosphere.

-16. The process of treating wood comprising sweating the wood to soften and heat it, thereafter submerging the wood and treating it in superheated water to dissolve and remove water soluble constituents, removing the water, and thereafter surrounding the wood by a'body of moderately heated moist atmosphere.

47. The process of treating wood comprising sweating the wood to soften and heat it, subsequently creating around the wood a body of steam under pressure to permeate the same and evaporate a portion of the moisture, and subsequently subjecting the wood to drying heat while removing excess moisture from around the wood.

48. The process of treating 'wood com rising sweating the wood to soften it, .t ereafter treating the wood to dissolve and remove water soluble constituents and evaporating moisture under vacuum and in a moist 7 atmosphere and causing the retained resins to spread throughout the wood structure.

49. The process of treating wood comprising sweating the wood to soften it, then alternately subjecting the wood to vacuum and super-heated water to dissolve and remove water soluble constituents and evaporate moisture, and subsequently treating the wood a in a heated moist atmosphere and moisture while drying.

In testimony whereof I affix my signature.-

FREDERICK K; FISH, JR. 

